Rechargeable batteries are commonly employed to supply power for portable electronic devices such as radios, notebook computers, cameras, etc. A rechargeable battery can be refreshed to full capacity if the rechargeable battery is charged by a power source such as an adapter. A battery management system may be employed to implement the charging function, and the battery management system can also provide protection function to protect the battery from any damage under some abnormal conditions, such as over voltage, over temperature, etc. In conventional solutions, the charging function and protection function for a battery management system are usually implemented by separate circuits, a circuit for the charging function and a circuit for the protection function.
The battery management system usually includes a detection circuit to monitor the capacity of the rechargeable battery, for example, the voltage value of the rechargeable battery. When the battery capacity is not full, the battery management system will charge the battery. When the battery is fully charged, the charging process will be terminated.
During the process of charging the rechargeable battery, if some abnormal conditions such as over voltage, over current or abnormal temperature occur, these abnormal conditions will considerably deteriorate the battery performance. So the protection function is needed to avoid abnormal conditions from deteriorating the battery. When an abnormal condition is detected, the protection operation, such as terminating the charging process, is activated to protect the battery.
In conventional battery management systems, the circuits designed for charging and protection functions are located on different chips. The circuit for the charging function may be integrated into one chip and sealed as an apparatus outside a battery package. The circuit for the protection function may be integrated into another chip and sealed with the battery inside the battery package. In these conventional applications, since two separate packages are needed for charging the rechargeable battery, it is not convenient enough especially for use by portable electronic devices. Some designers have tried to integrate both charging and protection functions into a single chip and seal the chip with the battery inside the battery package.
However, the simple combination of two circuits makes the chip size much larger. The chip integrating with both charging and protection functions is larger and much more complex than a chip with only one function. Sealing the combined chip within the battery package increases the size of the battery package even more. Therefore, it is needed an efficient system for providing the charging and protection functions to portable electronic devices, and it is to such system the present invention is primarily directed.